@@ -560,6 +560,22 @@ func (c *Manager) freeze(path string, state State) error {
560560 }
561561}
562562
563+ func (c * Manager ) isCgroupEmpty () bool {
564+ // In case of any error we return true so that we exit and don't leak resources
565+ out := make (map [string ]interface {})
566+ if err := readKVStatsFile (c .path , "cgroup.events" , out ); err != nil {
567+ return true
568+ }
569+ if v , ok := out ["populated" ]; ok {
570+ populated , ok := v .(uint64 )
571+ if ! ok {
572+ return true
573+ }
574+ return populated == 0
575+ }
576+ return true
577+ }
578+
563579// MemoryEventFD returns inotify file descriptor and 'memory.events' inotify watch descriptor
564580func (c * Manager ) MemoryEventFD () (int , uint32 , error ) {
565581 fpath := filepath .Join (c .path , "memory.events" )
@@ -568,32 +584,72 @@ func (c *Manager) MemoryEventFD() (int, uint32, error) {
568584 return 0 , 0 , errors .New ("failed to create inotify fd" )
569585 }
570586 wd , err := syscall .InotifyAddWatch (fd , fpath , unix .IN_MODIFY )
571- if wd < 0 {
587+ if err != nil {
588+ syscall .Close (fd )
589+ return 0 , 0 , fmt .Errorf ("failed to add inotify watch for %q: %w" , fpath , err )
590+ }
591+ // monitor to detect process exit/cgroup deletion
592+ evpath := filepath .Join (c .path , "cgroup.events" )
593+ if _ , err = syscall .InotifyAddWatch (fd , evpath , unix .IN_MODIFY ); err != nil {
572594 syscall .Close (fd )
573- return 0 , 0 , fmt .Errorf ("failed to add inotify watch for %q" , fpath )
595+ return 0 , 0 , fmt .Errorf ("failed to add inotify watch for %q: %w " , evpath , err )
574596 }
575597
576598 return fd , uint32 (wd ), nil
577599}
578600
579601func (c * Manager ) EventChan () (<- chan Event , <- chan error ) {
580602 ec := make (chan Event )
581- errCh := make (chan error )
603+ errCh := make (chan error , 1 )
582604 go c .waitForEvents (ec , errCh )
583605
584- return ec , nil
606+ return ec , errCh
585607}
586608
587- func (c * Manager ) waitForEvents (ec chan <- Event , errCh chan <- error ) {
588- fd , wd , err := c .MemoryEventFD ()
609+ func parseMemoryEvents (out map [string ]interface {}) (Event , error ) {
610+ e := Event {}
611+ if v , ok := out ["high" ]; ok {
612+ e .High , ok = v .(uint64 )
613+ if ! ok {
614+ return Event {}, fmt .Errorf ("cannot convert high to uint64: %+v" , v )
615+ }
616+ }
617+ if v , ok := out ["low" ]; ok {
618+ e .Low , ok = v .(uint64 )
619+ if ! ok {
620+ return Event {}, fmt .Errorf ("cannot convert low to uint64: %+v" , v )
621+ }
622+ }
623+ if v , ok := out ["max" ]; ok {
624+ e .Max , ok = v .(uint64 )
625+ if ! ok {
626+ return Event {}, fmt .Errorf ("cannot convert max to uint64: %+v" , v )
627+ }
628+ }
629+ if v , ok := out ["oom" ]; ok {
630+ e .OOM , ok = v .(uint64 )
631+ if ! ok {
632+ return Event {}, fmt .Errorf ("cannot convert oom to uint64: %+v" , v )
633+ }
634+ }
635+ if v , ok := out ["oom_kill" ]; ok {
636+ e .OOMKill , ok = v .(uint64 )
637+ if ! ok {
638+ return Event {}, fmt .Errorf ("cannot convert oom_kill to uint64: %+v" , v )
639+ }
640+ }
641+ return e , nil
642+ }
589643
590- defer syscall . InotifyRmWatch ( fd , wd )
591- defer syscall . Close ( fd )
644+ func ( c * Manager ) waitForEvents ( ec chan <- Event , errCh chan <- error ) {
645+ defer close ( errCh )
592646
647+ fd , _ , err := c .MemoryEventFD ()
593648 if err != nil {
594649 errCh <- err
595650 return
596651 }
652+ defer syscall .Close (fd )
597653
598654 for {
599655 buffer := make ([]byte , syscall .SizeofInotifyEvent * 10 )
@@ -604,48 +660,22 @@ func (c *Manager) waitForEvents(ec chan<- Event, errCh chan<- error) {
604660 }
605661 if bytesRead >= syscall .SizeofInotifyEvent {
606662 out := make (map [string ]interface {})
607- if err := readKVStatsFile (c .path , "memory.events" , out ); err == nil {
608- e := Event {}
609- if v , ok := out ["high" ]; ok {
610- e .High , ok = v .(uint64 )
611- if ! ok {
612- errCh <- fmt .Errorf ("cannot convert high to uint64: %+v" , v )
613- return
614- }
663+ if err := readKVStatsFile (c .path , "memory.events" , out ); err != nil {
664+ // When cgroup is deleted read may return -ENODEV instead of -ENOENT from open.
665+ if _ , statErr := os .Lstat (filepath .Join (c .path , "memory.events" )); ! os .IsNotExist (statErr ) {
666+ errCh <- err
615667 }
616- if v , ok := out ["low" ]; ok {
617- e .Low , ok = v .(uint64 )
618- if ! ok {
619- errCh <- fmt .Errorf ("cannot convert low to uint64: %+v" , v )
620- return
621- }
622- }
623- if v , ok := out ["max" ]; ok {
624- e .Max , ok = v .(uint64 )
625- if ! ok {
626- errCh <- fmt .Errorf ("cannot convert max to uint64: %+v" , v )
627- return
628- }
629- }
630- if v , ok := out ["oom" ]; ok {
631- e .OOM , ok = v .(uint64 )
632- if ! ok {
633- errCh <- fmt .Errorf ("cannot convert oom to uint64: %+v" , v )
634- return
635- }
636- }
637- if v , ok := out ["oom_kill" ]; ok {
638- e .OOMKill , ok = v .(uint64 )
639- if ! ok {
640- errCh <- fmt .Errorf ("cannot convert oom_kill to uint64: %+v" , v )
641- return
642- }
643- }
644- ec <- e
645- } else {
668+ return
669+ }
670+ e , err := parseMemoryEvents (out )
671+ if err != nil {
646672 errCh <- err
647673 return
648674 }
675+ ec <- e
676+ if c .isCgroupEmpty () {
677+ return
678+ }
649679 }
650680 }
651681}
0 commit comments